ProtonMail (unofficial)

Unofficial ProtonMail extension. Provides notifications and makes it possible to close the ProtonMail tab, and even the browser, without getting logged out.

General Settings:

Fetch interval: Select how many often the extension will check for new emails.

Settings:

Persist session: Check it to keep the sessions in browser memory.
Persist session even if browser is closed: Check it to save the sessions to disk. WARNING: Your mailbox password will be written to your hard drive.
Show unread count badge: A badge will show on the extension icon with the number of unread emails on the INBOX.
Show notifications on new emails: If checked then the extension will show a notification when you receive an email.